1. Field of the Invention
The present invention generally relates to an electrode structure of a semiconductor device. More particularly, the present invention is concerned with a semiconductor device having a through electrode incorporated therein and a method of manufacturing the semiconductor device incorporating the through electrode.
2. Related Art
In the semiconductor device known heretofore the through electrode such as mentioned above is fabricated by depositing a resist film having an opening on a semiconductor substrate, forming a column of an electrically conductive material through a plating process and fixing or consolidating the electrically conductive column by using a resin. For more particulars, reference may have to be made to Japanese Patent Application Laid-Open Publication No. 307937/1999 (page 7, FIG. 1).
In the semiconductor device having the through electrode manufactured as mentioned above, the electrode extending through the semiconductor substrate, i.e., the through electrode, is electrically isolated or insulated from the semiconductor substrate by an insulation film interposed therebetween. For manufacturing the semiconductor device of this type, a fine hole of a greater depth is formed with a large aspect ratio, whereon an insulation film having a high coating quality is formed on the inner wall of the hole by a chemical vapor deposition (CVD) method while a metal film serving as a cathode in an electroplating process is deposited with a high coating quality by a chemical vapor deposition (CVD) method.
After having filled the hole with a metal by electroplating by employing the metal film as a cathode, excessive insulation material deposited through the CVD process and excessive metal deposited by plating are removed. Thereafter, the semiconductor substrate is ground from the back side to expose the metal deposited on the bottom portion of the hole.
As is apparent from the above, in manufacturing the conventional semiconductor device, it is required to form the hole a large aspect ratio in the semiconductor substrate and then form the insulation film at least on the side or lateral wall of the hole with a high coating quality without any noticeable defects. In particular, however, it is technically very difficult to meet such requirement.
Further, the cathode material deposited by plating adheres not only the bottom portion of the hole but also the side wall. Consequently, when the metal is buried in the hole through the electroplating process, metal growth occurs not only from the hole bottom but also from the side wall of the hole. In general, since the metal grows from the side wall portion located at the top portion of the hole at a higher rate because of high fluidity, there may arise such unwanted situation that the top portion of the hole is firstly blocked by the metal in the course of plating, resulting in that the lower portion of the hole remains yet to be metalized. In order to evade such undesirable situation, it is necessary to control the metal growth, which control is however extremely difficult.
For the reasons mentioned above, great difficulties have been encountered heretofore in manufacturing the semiconductor device incorporating the through electrode, which has presented a great obstacle to wide-spreading of such semiconductor device. Besides, the yield and the operation reliability of the manufactured semiconductor device are very low. Additionally, high cost is involved in manufacturing the semiconductor device.